Remote Desktop software that works with audio (Windows)

Question

I've tried:

• Windows 7's built-in RDP / "Remote Desktop Connection" tool => works with audio, but there are crackles/pops, even with this trick and this one.

• UltraVNC => no audio support

• TightVNC => no audio support

• RealVNC Enterprise => very good audio support, no lag / no crackle, high quality ; but not free

Is there a "remote desktop" software for Windows that both:

• has good audio support

• is open-source or freeware

?